Modern telecommunications networks, such as the public switched telephone network (PSTN), depend on the fast and reliable exchange of control or signaling messages between various network nodes, such as telecommunication switches. Signaling System No. 7 (SS7) is primarily used in the PSTN to communicate such signaling using dedicated, out-of-band signaling channels. Out-of-band signaling is signaling that is not communicated over the same path as the data transfer (for example, a telephone conversation). Instead, a separate digital channel (a signaling link) is created so that signaling messages may be exchanged between network nodes.
Due to the ever-increasing growth of the Internet (and the resulting increase in its communication capacity), many experts have suggested that the Internet be used to communicate telecommunication signaling, such as SS7 signaling. In networks using the Internet Protocol (IP), such as the Internet, signaling messages are normally transported using the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). However, neither UDP, TCP, nor any other communication protocols fulfills all the requirements of a high-performance telecommunications signaling system.
According to the present invention, disadvantages and problems associated with previous systems and methods for retransmitting messages have been substantially reduced or eliminated.
According to one embodiment of the present invention, a method for retransmission of messages includes transmitting a first message from a source to a destination using a packet-based network. The destination is capable of transmitting an acknowledgement to the source indicating the receipt of the first message. The method also includes determining that the first message has not been acknowledged and periodically retransmitting the first message from the source to the destination. In doing so, the first message is bundled in a packet with a second message that is being transmitted from the source for the first time. Therefore, an additional packet is not created for the retransmission of the first message.
The system and method of the present invention provide a number of important technical advantages. For example, embodiments of the present invention provide for the periodic retransmission of messages using the Stream Control Transmission Protocol (SCTP) or other appropriate communication protocols without an associated increase (or with a limited increase) in the number of packets that are transmitted over the associated network (as currently exists when using such protocols). Since each packet transmitted over a network has an associated overhead, no matter how much data the packet contains, a reduction in the number of packets communicated using the network helps to reduce congestion in the network.
This advantage may be accomplished, at least in part, through the modification of existing protocols or the creation of a new protocol that allows periodic bundling of messages to be retransmitted with new messages being sent from a source. This bundling is effective since packets sent from a source are often not full (do not equal the maximum packet size) and thus messages to be retransmitted may be added to the outgoing packets. This bundling technique is especially effective if the messages to be transmitted are relatively small (as is the case with PSTN signaling messages), since such small messages are more likely to fit into the unoccupied space in the outgoing packets. However, any other appropriate types of messages may also be retransmitted using embodiments of the present invention. Furthermore, the periodic bundling of messages to be retransmitted with new messages may be accomplished in cooperation with existing retransmission techniques used by SCTP and similar protocols (such as the retransmission of packets based on retransmission timers and acknowledgement gaps). Other important technical advantages are readily apparent to those skilled in the art from the following figures, descriptions and claims.